Fracture Analysis Of TA3 Pure Titanium LC-DCP Bone Plate And Finite Element Simulation On Its Fracture Failure

Pure titanium bone plates are widely used in clinic to cure bone fracture due to their excellent mechanical properties,corrosion-resistance and biocompatibility matched to bones.With the complex physiological and mechanical environment in body,pure titanium bone plates occasionally suffer fracture,which directly affects the healing of bone fracture and causes delayed healing,non-union and even bone tissue necrosis.Therefore,it is very necessary to study the fracture behavior of pure titanium bone plates served in vivo,establish effective experimental and numerical simulation methods,and then reveal the fracture failure mechanism,which would provide theoretical supports for the improvement of clinical orthopedic surgery and the optimization design of orthopedic implants.In this study,12 clinically fractured TA3 pure titanium limited contact dynamic compression(LC-DCP)bone plates were collected and sterilized.The physical and chemical performance of these samples and their fracture surface morphologies were examined.Then,a three-dimensional finite element model of middle femoral transverse fracture treated by 10-hole TA3 pure titanium LC-DCP bone plate internal fixation,was established.With respect to different bone fracture gaps,fracture healing and bone plate stress were analyzed through numerical simulation.Finally,the fracture mechanism of TA3 pure titanium LC-DCP plates was revealed.Main results and conclusions are summarized as follows:(1)The physical and chemical properties of the 12 TA3 pure titanium LC-DCP bone plates are qualified.Fracture occurs around the middle screw hole of bone plate.Parallel fatigue striations and secondary cracks appear in the fracture surface and cracks propagate from the distal bone surface to the proximal surface.The failure of the bone plates is mainly due to brittle fracture,accompanied with fatigue fracture.(2)The results of finite element simulation show that the fracture failure of 10-hole TA3 pure titanium LC-DCP internal fixation bone plate is most likely to occur at the right edge of the 6th screw hole,which is consistent with the fracture location of the 12 bone plates in clinic.(3)The fracture failure of the 12 TA3 pure titanium LC-DCP bone plates is mainly resulted from patients walking prematurely.At the condition,the maximum shear stress at the middle screw hole located on bone plate's distal surface exceeds the yield strength of TA3 pure titanium so as to cause local defects.Then,fatigue fracture occurs to bone plates under the action of complex cyclic loading in body.Patients should not walk in postoperative 2 months when the fracture gap is less than 8 mm.When the gap equals or exceeds 8 mm,patients should not walk in postoperative 3 months.